ESTRO 36 Abstract Book

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S549 ESTRO 36
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Results
While in 2D cultures of 518A2 melanoma cells, the
comparator substance cilengitide showed to be more
efficient than our novel compound NIA (IC50 value of
0,65µM), it had no inhibitory effect in 3D spheroid culture
up to 50µM. Comparatively NIA revealed to have similar
effectiveness in 2D as well as 3D cultures, both in the low
micromolar range. During monitoring of spheroid growth,
NIA treated spheroids initially depicted a growth
retardation, before cells started to disintegrate and die.
The radiosensitivity of 518A2 melanoma cells was found to
be similar in both culture conditions.
Conclusion
Similar differences in drug response and efficacy between
2D and 3D cell culture environments have been reported
for various anti-cancer substances as well as for some
radiation exposure endpoints. However, other endpoints
may - in a treatment-related manner - be depending on
the culture system used. We thus plan to perform further
comparative studies on survival-dependent aspects
(apoptosis, intracellular signaling, and others) with
integrin antagonists alone as well as in combination with
irradiation in 2D cell culture versus 3D spheroids.
PO-0995 Estimation of radiobiology parameters of
infiltrative low-grade gliomas WHO Grade II.
S. Milyukov1, Y. Lysak2, G. Panshin2, N. Kharchenko 1, Z.
Tsallagova2, T. Izmailov2
1 Peoples’ Friendship University of Russia, Department of
oncology and roentgenoradiology, Moscow, Russian
Federation
2 Russian Scientific Center of Roentgenoradiology of
Russia, Research department of innovative technologies
of radiotherapy and chemoradiation treatment of
malignant tumors, Moscow, Russian Federation
Purpose or Objective
Determine the value of radiobiological parameters of
infiltrative low-grade gliomas WHO Grade II
Material and Methods
In total (the data from) 5 clinical studies: EORTC 22844
(Karim AB et al., 1996.), EORTC 22845 (van den Bent MJ
et al., 2005), NCCTG 86-72-51 (Shaw E et al., 2002), the
RTOG 9802 (Shaw EG et. al., 2012), the study on the
hyperfractionated radiotherapy (Jeremic B et. al., 1998),
and selected data from our database were used for the
calculation radiobiological parameters of LGG. In total,
our study included 870 patients. All patients received
surgery (1-phase treatment) and radiotherapy (2-phase
treatment). Following radiobiological parameters of
radiotherapy were used for the calculation: dose per
fraction, total dose of radiotherapy, total number of
treatment days, 5-year progression-free survival.
Results
Following radiobiological parameters of infiltrative low-
grade gliomas WHO Grade II were calculated: α, β, α/β,
Td, D prolif, Tk, N clonogens. Following values were
calculated (95% Cl): α (Gr – 1) = 0,096 (0,08–0,11), β (Gr –2)
= 0,014 (0,012-0,018), α/β (Gr) = 6,8 (4,3-9,2), Td (days) =
21,3 (18,3-26,4), Dprolif (Gr) = 0,27 (0,21-0,35), Tk (days) =
44 (34-55), N clonogens = 2,18·103 (1,2-5,3) ·103 .
Conclusion
The calculated values of radiobiological parameters give a
better idea of the biological properties of the low-grade
gliomas and estimate as accurately as possible of the total
dose of radiotherapy using a linear-quadratic model.
Poster: RTT track: Patient preparation, positioning and
immobilisation
PO-0996 Accuracy of an optical surface monitoring
device to reduce daily imaging of breast cancer
patients
J. Sharpe1, A. Tini1, A. Moreira1, I. Pytko1, C. Winter1, M.
Guckenberger 1, C. Linsenmeier 1
1University Hospital of Zurich, Radiation Oncology Clinic,
Zurich, Switzerland
Purpose or Objective
To further test the positioning accuracy of an optical
surface monitoring device called Align RT for the
treatment of breast cancer patients. The data will then be
analyzed to determine if the daily positioning with Align
RT is accurate enough to allow for fewer weekly MV
imaging of breast radiotherapy patients.
Material and Methods
16 breast cancer patients were treated using 3D tangential
fields. Patients were positioned supine on the breast
board using an optical surface detector (Align RT). After
positioning, MV imaging and bone match on the chest wall
was done to verify the patients position, and corrected
accordingly. All shifted values were recorded. The Align
RT system consists of 6 cameras, which acquire the
patients’ position in 2D, and a computer vision algorithm,
which reconstructs the image into 3D. The patients’
reference surface was imported from the CT scan and the
region of interest of the treated area was selected. The
patient was positioned by using the Monitoring mode in
Align RT and driving couch values until pre-shift Align RT
deltas were as close to zero as possible. The Vertical
(VRT), Lateral (LAT), Longitudinal (LNG) shift values
generated from the MV images equal to or less than 5mm
were marked as falling within our accepted tolerance for
breast patients. This data was further analyzed to
conclude if it would be acceptably accurate enough to
reduce daily imaging.
Results
Out of the 16 patients involved in the study, a total of 213
fractions were treated using Align RT. Of these fractions,
201 (94.4%) had MV shift values, in all directions, within
our 5mm tolerance. 209 of 213 fractions (98%) were within
a 6mm tolerance or less. The largest shift observed was
9.5mm in the lateral direction, however the most frequent
axis that fell out of tolerance were VRT and LNG. The most
failed fractions (fractions with shift greater than 5mm)
observed from an individual patient was 3 out of her 25
recorded fractions. 9 of the 16 patients were treated with
all fractions within tolerance.
Conclusion
The data was found to be very consistent across all
patients, with 9 from 16 patients having all MV shifts equal
to or less than 5mm in all directions after using Align RT
for positioning and the remaining having minimal fractions
outside this tolerance. This data suggests a strong
argument for reducing daily imaging with breast patients
being positioned with Align RT. Reducing daily imaging to
2-3 times per week in combination with daily positioning
using Align RT would then be valuable in reduction of both
excess dose to the patient and treatment time on the
Linear accelerator.
PO-0997 Improving shoulder positioning in a 5-points
mask.
L. Mesch 1, S. Hol1, G. D'Olieslager2, C. Buijs 1, D.
Washington1
1Dr. Bernard Verbeeten Instituut, Department of
Radiation Oncology, Tilburg, The Netherlands
2Dr. Bernard Verbeeten Instituut, Department of medical
Physics & Engineering, Tilburg, The Netherlands